remove ,
before where in query
$sql_query="UPDATE `table_users` SET `pass_word` = '".$_POST['pass_word']."',`Email` = '".$_POST['Email']."',`website` = '".$_POST['website']."' WHERE `SNo` = '$user_id'";
store query in $sql_query
because you not store update string into variable
without store in $sql_query
you run sql query
if(mysql_query($sql_query))
so store update query in $sql_query